Method and device for transferring data over GPRS network

ABSTRACT

A method and device according to the present invention reorders Logical Link Control (LLC) Packet Data Units (PDUs) when user data is transferred over the radio interface between a Mobile Station (MS) and a packet data network. An objection of the present invention is to provide a method and system for transferring user data over a network ensuring the best quality of service characteristics.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to transferring data over a radiointerface in General Packet Radio System (GPRS) networks.

BACKGROUND OF THE INVENTION

In wireless telecommunication systems information is transferred overthe radio interface between a transmitting and/or receivingcommunication device and a communication network. In General PacketRadio System (GPRS) networks, such as GPRS, Enhanced GRPS (EGPRS) andGSM Enhanced Data rate for Global Evolution (EDGE) Radio Access Network(GERAN) efforts has been made to improve the quality of the datatransfer and thus the quality of service (QoS). The term GPRS alsorelates to EGPRS, GERAN and other enhancements of the GPRS in thepresent application.

A mobile station (MS), a base station sub-system (BSS) comprising a basetransceiver station (BTS) and a base station controller (BSC) includinga Packet Control Unit (PCU), and a serving GPRS support node (SGSN) arethe main components of the GPRS architecture for communicating between aterminal device and the GPRS network. A gateway GPRS support node (GGSN)enables data transfer between the GPRS network and external datanetworks, such as an Internet. One or more GGSNs are connected to a SGSNvia Internet Protocol (IP) based GPRS backbone network. When the MScommunicates with external data networks, the GGSN operates as an IProuter between a MS and the external network. Packet data channels(PDCH) are used as physical channels for the packet data transfer in theGPRS. To transfer user data, i.e. other data not produced by the GPRSprotocols, a Packet Data Protocol (PDP) context is generated. Allmessages including PDP context messages are transferred using aTemporary Block Flow (TBF) between a MS and GPRS network.

The Logical Link Control (LLC) protocol is used to transfer data betweena MS and a SGSN in the GPRS network. The technical specifications of theLLC layer protocol to be used for Packet Data Transfer (PDT) between aMS and SGSN are defined in the document 3GPP TS 44 064 V 4.3.0 (2002-03)[1]. The LLC layer is independent of the underlying radio interfaceprotocol. The LLC protocol layer consists of Logical Link ManagementEntities (LLME), Logical Link Entities (LLE) and a multiplex procedure.A LLE is the LLC layer protocol state machine controlling one logicallink connection.

The LLC layer operates above a Radio Link Control (RLC) layer on the MSside and above a Base Station Sub-system GPRS Protocol (BSSGP) layer onthe SGSN side. Above the LLC layer is a SubNetwork Dependent Convergence(SNDC) protocol layer, that controls the transfer of user data Networklayer Packet Data Units (N-PDU) between a MS and SGSN. Also above theLLC layer locates a GPRS Mobility Management (GMM) protocol layer, thatuses the services of the LLC layer to transfer messages between a MS anda SGSN.

A MAC (Media Access Control) protocol layer locates under a RLC layer onthe MS side. It defines the procedures that enable multiple MSs to sharea common radio interface and it allows a MS to use several physicalchannels in parallel on the MS side of the GPRS network. The MAC alsoprovides the arbitration between multiple MSs simultaneously attemptingto access a radio interface.

A RLC/MAC layer protocol of the GPRS is described in the document 3GPPTS 44 060 V4.5.0 (2002-02) [2]. A R-LC/MAC block is a protocol data unitexchanged between RLC/MAC entities, and a RLC/MAC control block is apart of a RLC/MAC block carrying a control message between RLC/MACentities or RLC data block is a part of a RLC/MAC block carrying userdata or signaling data of upper layers. The RLC layer defines theprocedures for segmentation and reassembly of LLC PDUs into RLC/MACblocks and the RLC layer provides also link adaptation. The RLC/MAC isresponsible for transmitting LLC PDUs over the radio interface using aTemporary Block Flow (TBF), which is a physical radio connectionsupporting the unidirectional transfer of LLC PDUs between a MS and thenetwork. A LLC PDU contains user data or GPRS protocol related signalingmessages, such as a GMM signaling message (GMM/SM). A MS may have anuplink TBF (UL TBF), a downlink TBF (DL TBF) or an uplink and downlinkTBF established at any time. When a transfer mode of LLC PDUsterminates, in either uplink or downlink direction, the correspondingTBF is released and the MS returns to packet idle mode. When a transfermode of LLC PDUs terminates but there exists an on-going LLC PDUtransfer to the other direction, the MS stays in transfer mode.

One TBF may carry RLC data blocks only in one RLC mode at a time. Thismeans that when transferring in-sequence LLC PDUs utilizing differentRLC modes (ACK or UNACK), a previous TBF has to be released and a newTBF has to be established for a new RLC mode. The LLC is intended foruse with both acknowledged (LLC ACK) and unacknowledged (LLC UNACK) datatransfer and the RLC/MAC supports both the RLC ACK mode and RLC UNACKmode. The LLC modes and the RLC modes are independent from each other.In the LLC ACK mode the LLC provides a reliable service with in-orderdelivery but in the LLC UNACK mode the LLC does not guarantee in-orderdelivery. In RLC ACK mode RLC uses retransmissions to guaranteeerror-free transmission and in RLC UNACK mode retransmissions are notused. In both modes RLC/MAC specification says that upper layer PDUsshall be delivered in the order they are received from upper layers. InRLC UNACK mode one lost RLC data block may result in discarding of thewhole LLC PDU at the receiving side. In the RLS ACK mode Backward ErrorCorrection (BEC) procedures enable the selective retransmission ofunsuccessfully delivered RLC/MAC blocks.

According to the Technical Specifications 3GPP TS 44 064 V 4.3.0 [1] theRLC shall deliver LLC PDUs received from the upper layers in the sameorder as they were received from the upper layers. This means that LLCPDUs are delivered in the same order as received from the upper layers(i.e. LLC layer), regardless of the fact that some LLC PDUs may havee.g. higher priority than other LLC PDUs. This is a big problem whentransferring e.g. real-time or other delay sensitive data over the radiointerface, because the data, despite its high priority, have to hold onthe transmitting queue of in-order delivery. This may impair the QoS ofthe application.

The LLC allows data transfer with different service criteria, such thathigh-priority data transfers may take precedence over lower-prioritydata transfers to the same MS. A LLC PDU has certain QoS characteristicsconcerning the RLC mode, priority, throughput, etc. When streaming dataor otherwise delay sensitive data, such as speech, is transferred overthe GPRS network, it should be delivered before e.g. best effort data,such as FTP (File Transfer Protocol) data or web surfing, to ensure theQoS. Otherwise the service suffers bad quality. Recently an interesttowards transferring delay sensitive data over the GPRS network isrising.

An example is now provided to describe the current state of the priorart. Assume that the RLC/MAC of the MS first receives three short LLCPDUs from a delay sensitive application that needs to be transmittedusing the RLC UNACK mode. After this the RLC/MAC receives two long, e.g.1500 octet each, LLC PDUs containing FTP data that needs to betransmitted using the RLC ACK mode. Then after this the RLC/MAC againreceives three short LLC PDUs from the delay sensitive application thatneeds to be transmitted using the RLC UNACK mode. When changing atransfer mode from the RLC UNACK mode to the RLC ACK mode, first anexisting TBF is released, then a new TBF is established and then FTPtraffic LLC PDUs are transferred in RLC data blocks. After this atransfer mode is changed from the RLC ACK mode to the RLC UNACK modeagain by releasing existing TBF and establishing new TBF, and then atransfer of data packets of the delay sensitive application maycontinue. A time needed to transfer FTP traffic LLC PDUs in the RLC datablock depends on the number of assigned uplink PDCHs. The elapsed timealso depends on a channel coding scheme used to transfer RLC data blocksover the radio interface and how frequently the TBF is assigned sendingpermissions. In this example, a transfer of two 1500 octet long LLC PDUsin the RLC ACK mode between the delay sensitive data packets may takeseveral seconds. The gap of several seconds will result in that delaysensitive applications will substantially suffer from the FTP transfer.

The gap of several seconds will result in that a transfer of real timeLLC PDUs of applications using streaming or otherwise delay sensitivedata will be blocked by a transfer of non-real time LLC PDUs ofapplications using FTP or other best effort data according to thecurrent specifications. In case of a speech application the quality ofthe conversation becomes unacceptable. From the foregoing it followsthat the current GPRS network is unable to transfer delay sensitive dataover the radio interface.

There are significant problems related to prior art to transfer delaysensitive data over the GPRS network. Grounds for the problems in priorart is the fact that a RLC/MAC does not interprete contents of a LLC PDUat all, and it only transfers a LLC PDU, such as received from a LLC,over a radio interface.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a method and systemfor transferring user data over a network ensuring the best quality ofservice characteristics.

The objective of the present invention is fulfilled by prioritising apacked user data message delivery according to a data content of amessage and by associating the Packet Data Protocol (PDP) context to theradio interface access points via which the packed data message istransferred over the network.

In accordance with the present invention there is provided a methodrelated to a mobile station for transferring user data in a wirelesspacket data network, wherein the method comprises the steps of:

-   -   at a certain protocol layer, receiving a first packet data        message from an upper protocol layer, which first packet data        message belongs to a first packet data protocol (PDP) context        characterised by certain first connection information,    -   at said certain protocol layer, receiving a second packet data        message from an upper protocol layer, which second packet data        message belongs to a second packet data protocol (PDP) context        characterised by certain second connection information,    -   reordering said first packet data message and said second packet        data message said certain protocol layer according to a relative        urgency of transmission of said first and second packet data        protocol (PDP) contexts, and    -   delivering said first packet data message and said second packet        data message further from said certain protocol layer in        reordered order.

In accordance with the present invention there is provided a mobilestation (MS) for transferring user data in a wireless packet datanetwork, the mobile station (MS) comprising a transceiver fortransmitting and receiving packet data messages, wherein the mobilestation (MS) comprises:

-   -   a controller configured to generate packet data protocol context        activation messages for informing the network about the        activation of packet data protocol (PDP) contexts for user data        transmission, and    -   a layered transmission protocol arrangement comprising a certain        protocol layer entity as well as higher protocol layer entities,        of which said certain protocol layer entity is configured to        receive packet data messages belonging to different packet data        protocol (PDP) contexts from at least one upper protocol layer,        to reorder packet data messages received from at least one upper        protocol layer according to a relative urgency of transmission        of packet data protocol (PDP) contexts that the packet data        messages belong to, and to deliver packet data messages further        from said certain protocol layer in reordered order.

In accordance with the present invention there is provided a methodrelated to a network element of a wireless network for transferring userdata between a mobile station (MS) and a wireless packet data network,wherein the method comprising the steps of:

-   -   at a certain protocol layer, receiving a first packet data        message from an upper protocol layer, which first packet data        message belongs to a first packet data protocol (PDP) context        characterised by certain first connection information,    -   at said certain protocol layer, receiving a second packet data        message from an upper protocol layer, which second packet data        message belongs to a second packet data protocol (PDP) context        characterised by certain second connection information,    -   reordering said first packet data message and said second packet        data message at said certain protocol layer according to a        relative urgency of transmission of said first and second packet        data protocol (PDP) contexts, and    -   delivering said first packet data message and said second data        message further from said certain protocol layer in reordered        order.

In accordance with the present invention there is provided a networkelement of a wireless network for transferring user data between amobile station (MS) and a wireless packet data network, wherein networkelement comprises:

-   -   a controller configured to generate packet data protocol (PDP)        context activation messages for informing the network about the        activation of packet data protocol (PDP) contexts for user data        transmission, and    -   a layered transmission protocol arrangement comprising a certain        protocol layer entity as well as higher protocol layer entities,        of which said certain protocol layer entity is configured to        receive packet data messages belonging to different packet data        protocol (PDP) contexts from at least one upper protocol layer,        to reorder packet data messages received from at least one upper        protocol layer according to a relative urgency of transmission        of packet data protocol (PDP) contexts that the packet data        messages belong to, and to deliver packet data messages further        from said certain protocol layer in reordered order.

Some embodiments of the invention are described in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Next the present invention will be described in greater detail withreference to exemplary embodiments in accordance with the accompanyingdrawings, in which:

FIG. 1 illustrates a block diagram of a mobile station (MS) according toan embodiment of the present invention.

FIG. 2 illustrates a flow diagram of a method according to the presentinvention.

DETAILED DESCRIPTION

A preferred embodiment of the present invention is prioritising ofLogical Link Control (LLC) Packet Data Units (PDUs) when user data istransferred over the radio interface between the Mobile Station (MS) andthe GPRS network. According to the invention LLC PDUs are reorderedbased on their requirements.

According to one embodiment of the invention a Radio Link Control/MediaAccess Control (RLC/MAC) is able to reorder LLC PDUs inside a RLC/MACand a LLC associates a Packet Data Protocol (PDP) context to a LLCService Access Point Indicator (SAPI) intelligently. The presentinvention enables a LLC PDU to be prioritised in RLC/MAC and thus itenables applications to receive the quality of service (QoS) they need.Based on the additional QoS information received along the LLC PDU,RLC/MAC unit is able to prioritise LLC PDUs according to their urgencyof transmission in relation to other LLC PDUs.

According to another embodiment of the invention LLC PDUs are reorderedelsewhere than in a RLC/MAC.

In the following description reordering in a RLC/MAC is used as anexample.

FIG. 1 shows a block diagram of an embodiment of wireless communicationsystem 3 comprising at least one mobile station (MS) 10, a network 50and a radio link connection 40 according to the present invention. Onthe network side of the wireless communication system 3 there is alsoillustrated in FIG. 1 a Serving General Packet Radio Service (GPRS)Support Node (SGSN) 55 provided by a wireless network operator, at leastone base station controller (BSC) 54 including a Packet Control Unit PCUand at least one base transceiver station (BTS) 51 including antenna 53to wirelessly communicate with the MS 10 over the radio interface inaccordance with a predetermined radio interface specifications. A BTS 51and BSC 54 are included to a Base Station Sub-system (BSS) 52. The radiointerface 40 enables to transfer both voice and data traffic, includingan Internet access and web browsing. At least one gateway GPRS supportnode (GGSN) 58, connected to a SGSN 55 via IP-based GPRS backbone,provides a connection to external data networks 61. According to thepresent invention the radio interface supports, but is not limited to,General Packet Radio System (GPRS) networks, such as GPRS, Enhanced GRPS(EGPRS), GSM (Global System for Mobile communications) Enhanced Datarate for Global Evolution (EDGE) Radio Access Network (GERAN) and anyother enhancements of the GPRS or GSM or combinations thereof. The termGPRS relates to all those in this present application.

In FIG. 1 a MS 10 may be a handheld radiotelephone, such as a cellularphone, a personal communicator or alike. The MS 10 typically includes amicrocontroller unit (MCU) 11 coupled to a display unit 12 and akeyboard unit 13 for a user interface (as well as a microphone andspeaker). The MS 10 also contains a digital signal processor (DSP) 17 orequivalent, and a wireless transceiver unit 18 including transmitter,receiver and antenna 19 functions. The MCU 11 is connected to a memory14 for storing an operation program, received packet data, packet datato be transmitted, and the like. In association with the memory 14 is abuffer unit 15 for storing packet data messages into a transfer queueand for delivering packet data messages from the buffer to provide anin-order delivery of packet data messages according to the presentinvention.

The memory 14 also includes a Read-Only Memory (ROM) which inassociation with the MCU 11 provides a Radio Link Control/Medium AccessControl (RLC/MAC) unit 11 a, a SubNetwork Dependent Convergence Protocol(SNDCP) unit 11 c for user data transfer, a GPRS Mobility Management(GMM) unit 11 d and a Logical Link Control (LCC) unit 11 b to store aprogram enabling the MCU 11 to execute software routines, layers andprotocols required to implement the methods according to the presentinvention. The SNDCP unit 11 c and GMM unit 11 c are locating on thesame protocol layer. On the network 50 side in association with the BSC54 are a RLC/MAC unit 54 a and a BSSGP unit 54 b, and in associationwith the SGSN 55 are a BSSGP unit 55 a, a LLC unit 55 b, a SNDCP unit 55c, and GMM unit 55 d. Functional operation of these units is alsocontrolled by software instructions from the network operator'spremises. The SNDCP unit 55 c and GMM unit 55 d are locating on the sameprotocol layer.

In the GPRS network a packet data message is always transferred via aLLC layer which operates above RLC and BSSGP layers to provide logicallinks between a MS and its SGSN. Messages transferred via a LLC layerare called LLC packet data unit (LLC PDU) messages. Above a LLC layer ise.g. a SNDC protocol layer which controls the transfer of user databetween a MS and SGSN. A data link connection of a LLC layer to provideservices e.g. to the GMM and SNDC protocol layers is identified by aService Access Point Identifier (SAPI) both on the SGSN and MS side. TheSAPI is carried in the address field of the frame header of each LLCframe. LLC PDUs are segmented and reassembled into RLC/MAC blocksdefined by a RLC layer. A TBF allocated on one or more PDCHs comprises anumber of RLC/MAC blocks carrying one or more LLC PDUs. A TBF istemporary and is maintained only for a duration of the data transfer.

When LLC Packet Data Units (LLC PDU) are transferred between a MS 10 andBSS 52 and between a BSS 52 and SGSN 55 a LLC Relay provides services tothe RLC layer protocol. An LLC layer connection is identified viaService Access Points (SAP) in the LLC layer. In case the RLC/MAC unit54 a of the network is located in the BSS 52, the LLC relay operatesabove the RLC/MAC. In case RLC/MAC unit is located in the SGSN, the LLCoperates directly above the RLC/MAC. According to specifications [1] theRLC/MAC may be located in the network in the BTS, BSC or SGSN.

A SAP Identifier (SAPI) is used to identify a SAP on the SGSN side ofthe LLC interface and on the MS side of the LLC interface. In a LLCframe a SAPI includes an address field which is part of a frame header(LLC header). The SAPI identifies upper layer entity that receives a LLCPDU, e.g. a GMM, SMS, SNDCP. For example, if a SAPI is equal to 1(SAPI=1), this LLC PDU goes to the GMM. A SAPI is also used as aninternal LLC information in order to be able to handle PDUs withappropriate QoS characteristics. For example, when a SNDCP PDU usingNSAPI (NSAPI is a PDP context ID) is received from a SNDCP, the PDU istransferred e.g. using the LLC SAPI=3 and during the PDP contextactivation procedure certain QoS characteristics have been associated tothe PDP context.

FIG. 2 shows a flow diagram of an embodiment of a method related to amobile station (MS) for transferring user data in a wireless packet datanetwork according to the present invention. The present inventionimproves a way to transfer real-time (RT) and otherwise delay sensitivedata over radio interface between the MS and the SGSN enablingapplications to receive service they need.

In step 201 the MS 10 generates a protocol activation message forinforming the network to activate a packet data protocol (PDP) contextfor user data transmission. To do this, the GMM unit 11 d generates aGMM/SM message “Activate PDP Context Request” and moves it to the LLCunit 11 b to pack it to be a LLC PDU message. The LLC unit 11 bassociates a LLC PDU message to the LLC GMM SAPI and defines a LLC modeto be used to transfer the LLC PDU message. The LLC modes are a LLC ACKmode and LLC UNACK mode which are independent of a RLC mode. Then LLCunit 11 b moves the LLC PDU message to the RLC/MAC unit 11 a to transferit over the network.

Then the MS 10 in step 203 sends to the network “Activate PDP ContextRequest” message. The RLC/MAC unit 11 a transfers this LLC PDU messageconsisting a LLC header including a SAPI to the RLC/MAC unit 54 alocating in the BSC 54 where it is transmitted to the SGSN 55 accordingto step 204. LLC unit 55 b identifies the SAPI from the LLC header ofthe LLC PDU message. Then the LLC unit 55 b moves a data content of theLLC PDU to the GMM/SM unit 55 d according to the SAPI. Next, the GMM/SMunit 55 d either accepts or rejects the request by transmitting amessage “Activate PDP Context Accept” (step 205) or “Activate PDPContext Reject” (step 206). If the GMM/SM unit 55 d accepts the PDPcontext activation, all information needed to route a user data isavailable to all GPRS network entities. E.g. a GGSN knows the IP addressto be used and can route user data packets to the right SGSN serving theMS (GGSN is unaware of LLC). In association with activating PDP contextQoS characteristics are also defined for the PDP context (and user datatransferred using the PDP context).

When a PDP context is activated in step 207, the LLC unit 55 bassociates the PDP context to a LLC SAPI based on QoS requirements ofthe PDP context according to the Technical Specifications 3GPP TS 23.060V 3.12.0 “General Packet Radio Service (GPRS); Service description” [3].It says about multiplexing of N-PDUs from one or several NSAPIs onto oneLLC SAPI that NSAPIs which are multiplexed onto the same SAPI shall usethe same radio priority level, QoS traffic handling priority, andtraffic class. This means that if a MS has two active PDP contexts, thePDP context transferring delay sensitive data and the PDP contexttransfering best effort data can't be associated to the same SAPIaccording to specifications. Thus, different PDP contexts shall use adifferent LLC SAPI and similar PDP contexts may use the same LLC SAPI.However in case of two quite similar PDP contexts, they may also bedefined to use a different LLC SAPI in order to be able to reorder LLCPDUs belonging to different PDP contexts. An example: two streaming PDPcontexts are activated, one carries voice and the other carries video.Usually if a video gets stuck for a while, it doesn't matter as much asif there's a break in voice. Therefore by prioritising voice over videoin this case, we obtain better result.

When transferring user data a SNDCP unit 55 c becomes active instead ofa GMM unit 55 d. In step 209 a SNDCP unit 55 c receives a user datapacket. Then it segments a user data packet and transfers it to the LLCunit 55 b. The user data packet carries a NSAPI identifier of the PDPcontext. A NSAPI is one way to identify data belonging to different PDPcontext. Because a SNDCP and LLC share an internal interface, the LLCunit knows on the basis of the NSAPI to which LLC SAPI the user datapacket must be connected. After this the LLC unit 55 b packs the userdata packet to a LLC PDU message containing the user data a LLC headerand a frame check sequence (FCS). FCS is used to detect bit errors inthe frame header and user data field. In this phase the LLC unit 55 blabels the LLC PDU message with a LLC window number, on the basis onwhich a receiving LLC unit 11 b can process the LLC PDU messageproperly. The LLC unit 55 b then passes the LLC PDU message to theRLC/MAC unit 54 a. The LLC PDU message contains information how theRLC/MAC unit has to process it. This information includes e.g. a RLCmode, throughput and priority information. According to this informationRLC/MAC unit 54 a is able to transfer the LLC PDU over the radio inappropriate way. A new TBF may not have to be established in case therealready exists one.

Then in step 211 the RLC/MAC unit 54 a reads a LLC SAPI from the LLCheader of each LLC PDU message containing user data packets and reorderscertain LLC PDU messages on the basis of the LLC SAPI. Based on LLC PDUa RLC/MAC unit is able to read which LLC SAPI the LLC PDU uses. Based onthe additional QoS information received along the LLC PDU, RLC/MAC unitis able to prioritise LLC PDUs not utilizing the same LLC SAPI. TheRLC/MAC unit doesn't know what kind of QoS characteristics are used fora certain LLC SAPI, but the information is received along the LLC PDU.When a PDP context has been associated to a certain LLC SAPI, all LLCPDUs associated to this PDP context are routed via LLC layer using thissame LLC SAPI.

When RLC/MAC unit receives LLC PDU, the RLC/MAC checks if it has alreadybuffered LLC PDUs (steps 211 and 217). In case there are buffered LLCPDUs and the received and the buffered LLC PDUs utilize different LLCSAPI or the same LLC SAPI but different LLC mode (ACK/UNACK), RLC/MAC isable to reorder the LLC PDUs according to their QoS requirements (steps215). The LLC PDU with higher QoS information is transmitted (steps 213and 215) before the LLC PDU with lower QoS information (step 219).

An example:

A RLC/MAC buffer 15 situation in the beginning: (head) SAPI=7, SAPI=7,SAPI=7 (tail)

A new LLC PDU with LLC SAPI=3 is received. According to QoS receivedalong the LLC PDUs, if QoS of LLC PDU using SAPI=3 is higher than QoS ofLLC PDUs using LLC SAPI=7, a RLC/MAC buffer looks like:

RLC/MAC buffer 15 situation: (head) SAPI=3, SAPI=7, SAPI=7, SAPI=7(tail)

Otherwise if QoS of a LLC PDU using SAPI=3 is lower than QoS of LLC PDUsusing LLC SAPI=7, a RLC/MAC buffer looks like:

RLC/MAC buffer 15 situation: (head) SAPI=7, SAPI=7, SAPI=7, SAPI=3(tail)

The RLC/MAC unit 54 a of the network indicates to the RLC/MAC unit 11 a,and vice versa, if the RLC ACK mode or the RLC UNACK mode is to be used.When using RLC ACK mode the MS 10 can be sure that a transferred LLC PDUis received by the network 50. A transmitting RLC/MAC unit always tellsa receiving RLC/MAC unit in association a TBF establishment which RLCmode is used to transfer LLC PDUs.

Throughput of RT data should be ensured and NRT data should be bufferedin case there is RT data to be transmitted. An advantage of reorderingLLC PDUs compared to the FTP example described in the background sectionof prior art is that RT data is transmitted before NRT data and thus RLCmode doesn't have to be changed in the middle of the TBF (TBF releaseand establishments) in case RT data and NRT data use different RLC mode.

If during data transfer LLC PDU using different RLC mode than the oneused with existing TBF is received, MS/PCU 10, 54 shall check if thesending of the LLC PDU may be delayed and possibly if LLC PDUs may bereorganized. Only after transferring LLC PDUs having higher priority,the LLC PDUs using different RLC mode shall be transmitted.

In case RLC/MAC unit 54 a has reorganized and delayed the transmissionof LLC PDU transmission not carrying high priority data, RLC/MAC unitshall be able to determine when it may transmit the delayed LLC PDUs notcarrying high priority data. There are three alternative ways to detectan end of a high priority data transfer:

One alternative is that after sending the last LLC PDU carrying highpriority data RLC/MAC unit 54 a starts transmitting LLC PDUs notcarrying high priority data. As soon as new high priority data isreceived, RLC/MAC unit finishes the ongoing transmission of LLC PDU notcarrying high priority data and after that continues transmission withLLC PDUs carrying high priority data. This alternative creates somedelay between two subsequent high priority data packets, depending onthe length and RLC mode of the LLC PDU not carrying high priority data.

Another solution to the problem is that after sending the last LLC PDUcarrying high priority data RLC/MAC unit 54 a starts a timer with shorttimeout value (e.g. 100-200 ms). If the timer expires and RLC/MAC unithasn't received new high priority data, RLC/MAC is allowed to starttransmission of LLC PDUs not carrying high priority data.

A third alternative is that the RLC/MAC unit 54 a waits until highpriority frames in RLC/MAC buffer 15 have been transmitted. In caseRLC/MAC unit runs (temporarily) out of high priority data, RLC/MACstarts to transmit other LLC PDUs located in RLC buffer. If RLC receivesnew high priority data during transmission of low priority data, RLC/MACunit could interrupt transmission of the current LLC PDU by generatingLLC PDU border into RLC data block and continue transmitting LLC PDUscarrying high priority data in order to avoid delayes in high prioritydata transmission. A downside of this solution is that a fake LLC PDUborder might create confusion in LLC (however most likely LLC PDU CRC(FCS) checking would fail).

In the receiving end a SNDCP unit 11 c receives a LLC PDU containinguser data packet. Then it segments a user data packet and transfers itto the LLC unit 11 b. LLC PDUs are buffered into the transfer queue 15in association with the memory 14. When a LLC unit 55 b sends a LLC PDUto peer LLC unit 11 b via RLC/MAC, a LLC unit 11 b receiving thetransmitted LLC PDU checks that it receives LLC PDUs in-sequence order,what is needed not to break the operation of the LLC layer. Thischecking is based on a window number inside a LLC header of the LLC PDU.The window number is also used to check if received LLC PDU is aduplicate or a new LLC PDU. The window number increments by one (1)every time when a new LLC PDU is transmitted from LLC unit 11 b to theRLC/MAC unit 11 a and thus LLC unit 11 b checks that the window numberof a received LLC PDU also increments in-sequence order (1, 2, 3, . . .). Each LLC SAPI has its own series of window numbers, i.e. LLC SAPI 1has window numbers (1, 2, 3, . . . ), LLC SAPI 2 (1, 2, 3, . . . ), . .. , LLC SAPI 5 (1, 2, 3, . . . ), etc. In case the window number of thereceived LLC PDU increments in-sequence order, the LLC PDU istransferred to the transfer queue buffer 15. If the window number of thereceived LLC PDU (e.g. 1) was smaller than that of the previous LLC PDU(e.g. 50), i.e. the in-sequence order in not valid, the received LLC PDUmay be discarded. The RLC/MAC unit 11 a only transfers the LLC PDUmessage and it doesn't concern the contents of the LLC PDU message.

The MS 10 may also propose a LLC SAPI to be used with the PDP contextbut in any case the SGSN 55 determines a used LLC SAPI eventually.

A feature according to a method of the present invention may beimplemented in a mobile station (MS) 10, in a Serving General PacketRadio Service (GPRS) Support Node (SGSN) 55, and in a Packet ControlUnit (PCU) containing network RLC/MAC 61 in association with a BaseStation Controller (BSC) 53 or a mobile switching center (MSC).

The invention is not restricted to the embodiments described above.While a preferred embodiment of the present invention is disclosedherein for purposes of explanation, numerous changes, modifications,variations, substitutions and equivalents in whole or in part should nowbe apparent to those skilled in art to which the invention pertains.Substitutions of elements from one described embodiment to another arealso fully intended and contemplated. Accordingly, it is intended thatthe present invention be limited only the spirit and scope of the heretoappended claims.

1. A method comprising: at a radio link control/medium access controlprotocol layer, receiving at least one logical link control packet dataunit from an upper protocol layer, wherein each logical link controlpacket data unit belongs to a certain packet data protocol contextassociated with logical link control connection information and whereinquality of service information relating to the logical link controlconnection information is defined for the certain packet data protocolcontext, reordering each logical link control packet data unit the radiolink control/medium access control protocol layer according to arelative urgency of transmission of the logical link control packet dataunit with respect to a buffered logical link control packet data unitbased on at least the logical link control connection information andthe quality of service information, and delivering the received logicallink control packet data unit and the buffered logical link controlpacket data unit further from the radio link control/medium accesscontrol protocol layer in reordered order, wherein the method isperformed by a mobile station to transfer user data in a wireless packetdata network.
 2. A method according to claim 1, further comprising,after receiving each logical link control packet data unit, determiningwhether the radio link control/medium access control protocol layeralready comprises at least one buffered logical link control packet dataunit.
 3. A method according to claim 1, wherein the logical link controlconnection information of the received logical link control packet dataunit and the logical link control connection information of the bufferedlogical link control packet data unit are different.
 4. A methodaccording to claim 1, wherein the logical link control connectioninformation of the received logical link control packet data unit andthe logical link control connection information of the buffered logicallink control packet data unit are similar and the quality of serviceinformation of the received logical link control packet data unit andthe quality of service information of the buffered logical link controlpacket data unit are different.
 5. A method according to claim 1,further comprising, in response to the logical link control connectioninformation of the received logical link control packet data unit andthe logical link control connection information of the buffered logicallink control packet data unit being similar and the quality of serviceinformation of the received logical link control packet data unit andthe quality of service information of the buffered logical link controlpacket data unit being quite similar, changing the 1ogica1 link controlconnection information of the received logical link control packet dataunit.
 6. A method according to claim 5, wherein the received logicallink control packet data unit carries voice data and the bufferedlogical link control packet data unit carries video data.
 7. A methodaccording to claim 1, wherein at the upper protocol layer the logicallink control connection information is used as internal logical linkcontrol information in order to handle the logical link control packetdata unit with appropriate quality of service characteristics.
 8. Amethod according to claim 1, Wherein the received logical link controlpacket data unit at the radio link control/medium access controlprotocol layer comprises a logical link control header which indicatesat least one service access point indicator at the upper protocol layerand the radio link control/medium access control protocol layer readsthe indicated service access point indicator.
 9. A method according toclaim 8, wherein the logical link control header further indicates awindow number specific to the service access point indicator at theupper protocol layer and the window number is incremented by one whenthe upper protocol layer transmits the logical link control packet dataunit to the radio link control/medium access control protocol layer. 10.A method according to claim 9, wherein the upper protocol layer receiveseach logical link control packet data unit from the radio linkcontrol/medium access control protocol layer in a sequence orderaccording to the window number.
 11. A method according to claim 1,wherein the logical link control connection information is a serviceaccess point indicator.
 12. A method according to claim 5, wherein thelogical link control connection information is changed to be an unusedservice access point indicator point indicator.
 13. A method accordingto claim 1, wherein delivering further comprises buffering the receivedlogical link control packet data unit into a packet data transfer queuefor a period of time a current logical link control packet data unitdelivery is on-going.
 14. A method according to claim 1, whereindelivering further comprises, after ending transmission of a currentlogical link control packet data unit carrying a higher relative urgencyof transmission, at the radio link control/medium access controlprotocol layer starts a timer with a predetermined timeout value andafter the timer expires,. the radio link control/medium access controlprotocol layer initiates transmission of a logical link control packetdata unit carrying a lower relative urgency of transmission if the radiolink control/medium access control protocol layer has not received a newlogical link control packet data unit message carrying a higher relativeurgency of transmission during the predetermined timeout value.
 15. Amethod according to claim 1, wherein delivering further comprises,during transmission of the current logical link control packet data unitcarrying the lower relative urgency of transmission, interrupting thetransmission by, the radio link control/medium access control protocollayer in response to the radio link control/medium access controlprotocol layer receiving a new logical link control packet data unitcarrying a higher relative urgency of transmission, and initiatestransmission of the new logical link control packet data unit carryingthe higher relative urgency of transmission.
 16. A method according toclaim 15, wherein the logical link control packet data unit carrying thelower relative urgency of transmission is buffered by generating alogical link control packet data unit border into a radio link controldata block.
 17. A method according to claim 1, wherein the wirelesspacket data network is a general packet radio service Radio Servicenetwork.
 18. A method according to claim 1, wherein the network elementis one of a Serving General Packet Radio Support Node, a base stationcontroller, mobile switching center and where a packet control unitcomprises a radio link control/medium access control unit.
 19. A methodaccording to claim 1, wherein the quality of service information relatesto a logical link control mode defined in the upper protocol layer. 20.A mobile station comprising a transceiver configured to transmit andreceive packet data messages, a controller configured to generate packetdata protocol context activation messages informing the network aboutthe activation of packet data protocol contexts for transmission of atleast one logical link control packet data unit comprising user data,each packet data protocol context defines logical link controlconnection information relating to an urgency of transmission, a layeredtransmission protocol-arrangement comprising a radio link control/mediumaccess control protocol layer entity as well as higher protocol layerentities, of which the radio link control/medium access control protocollayer entity is configured to receive from at least one upper protocollayer logical link control packet data units, wherein each logical linkcontrol packet data unit belongs to a certain packet date protocolcontext associated with logical link control connection information andwherein quality of service information relating to the logical linkcontrol connection information is defined for the certain packet dataprotocol context, the radio link control/medium access control protocolentity is configured to reorder each received logical link controlpacket data unit from at least one upper protocol layer according to arelative urgency of transmission of logical link control packet dataunit with respect to a buffered logical link control packet data unitbased on at least the logical link control connection information andthe quality of service information, and the radio link control/mediumaccess control protocol entity is configured to deliver the receivedlogical link control packet data unit and the buffered logical linkcontrol packet data unit further from the radio link control/mediumaccess control protocol layer in reordered order.
 21. A mobile stationaccording to claim 20, wherein the mobile station is configured, inresponse to receiving a logical link control packet data unit, todetermine whether the radio link control/medium access control protocollayer entity already comprises at least one buffered logical linkcontrol packet data unit.
 22. A mobile station acc6rding to claim 20,wherein the logical link control connection information of the receivedlogical link/control packet data unit and the logical link controlconnection information of the buffered logical link control packet dataunit is different.
 23. A mobile station according to claim 20, whereinthe logical link control connection information of the received logicallink control packet data unit and logical link control connectioninformation of the buffered logical link control packet data unit aresimilar and the quality of service information of the received logicallink control packet data unit and the quality of service information ofthe buffered l6gical link control packet data unit are different.
 24. Amobile station according to claim 20, where the mobile station isconfigured, in response to the logical link control connectioninformation of the, received logical link control packet data unit andthe logical link control connection information of the buffered logicallink control packet data unit being similar and the quality of serviceinformation of the received logical link control packet data unit andthe quality of service information of the buffered logical link controlpacket data unit being quite similar, to change the logical link controlconnection information of the received logical link control packet dataunit.
 25. A mobile station according to claim 24, wherein the receivedlogical link control packet data unit carries voice data and thebuffered logical link control packet data unit carries video data.
 26. Amobile station according to claim 20, wherein at the upper protocollayer entity is configured to use the logical link control connectioninformation as an internal logical link control information in order tohandle the logical link control packet data unit with appropriatequality of service characteristics.
 27. A mobile station according toclaim 20, wherein the received logical link control packet data unit atthe radio link control/medium access control protocol layer entitycomprises a logical link control header which indicates at least aservice access s point indicator at the upper protocol layer entity andthe radio link control/medium access control protocol layer entity isconfigured to read the service access point indicator.
 28. A mobilestation according to claim 27, wherein the logical link control headerfurther indicates a window number specific for the service access pointindicator at the upper protocol layer entity and the window number isincremented by one when the upper protocol layer entity transmits thelogical link control packet data unit to the radio link control/mediumaccess control protocol layer entity.
 29. A mobile station according toclaim 28, wherein the upper protocol layer entity receives each logicallink control packet data unit from the radio link control/medium accesscontrol protocol layer entity in-sequence order according to the windownumber.
 30. A mobile station according to claim 20, wherein the logicallink control connection information is a service access point indicator.31. A mobile station according to claim 24, wherein the logical linkcontrol connection information is changed to be an unused service accesspoint indicator.
 32. A mobile station according to claim 20, wherein themobile station further comprises a buffer configured to buffer thereceived logical link control packet data unit into a packet datatransfer queue for a period of time while a current logical link controlpacket data unit delivery is on-going.
 33. A mobile station according toclaim 20, wherein the mobile station further comprises a timer with apredetermined timeout value configured to start after endingtransmission of the current logical link control packet data unitcarrying the higher relative urgency of transmission.
 34. A mobilestation according to claim 20, wherein the radio link control/mediumaccess control protocol layer entity is configured to interrupt atransmission of a current logical link control packet data unit carryinga lower relative urgency of transmission in response to receiving a newlogical link control packet data unit carrying, a higher relativeurgency of transmission during the transmission.
 35. A mobile stationaccording to claim 34, wherein the radio link control/medium accesscontrol protocol layer entity is configured to buffer the logical linkcontrol packet data unit carrying the lower relative urgency oftransmission by generating a logical link control packet data unitborder into a radio link control data block.
 36. A mobile stationaccording to claim 20, wherein the wireless packet data network is ageneral packet radio service network.
 37. A mobile station according toclaim 20, wherein the quality of service information relates to logicallink control mode defined in the upper protocol layer entity.
 38. Anetwork element comprising: a controller configured to generate packetdata protocol context activation messages configured to inform a networkabout activation of packet data protocol context for user datatransmission, a layered transmission protocol arrangement comprising aradio link control/medium access control protocol layer entity andhigher protocol layer entities, where the radio link control/mediumaccess control protocol layer entity is configured: to receive logicallink control packet data units from at least one upper protocol layerwherein each logical link control packet data unit belongs to a certainpacket data protocol context associated with logical link controlconnection information and wherein quality of service informationrelating to the logical link control connection information is definedfor the certain packet data protocol context, to reorder each receivedlogical link control packer data unit from at least one upper protocollayer according to a relative urgency of transmission of the logicallink control packet data unit with respect to a buffered logical linkcontrol packet data unit based on at least the logical link controlconnection information and the quality of service information, and todeliver the received logical link control packet data unit and thebuffered logical link control packet data unit further from the radiolink control/medium access control protocol layer in reordered order.39. A network element according to claim 38, wherein the controller isfurther configured to receive an uplink temporary block flow and, inresponse to receiving the uplink temporary block flow, to configure thepacket data protocol context activation messages.
 40. A network elementaccording to claim 38, wherein the controller is further configured todetermine, during reception, whether the logical link control packetdata units are received in-sequence order according the logical linkcontrol connection information of The logical link control packet dataunits.
 41. A network element according to claim 38, wherein afterreceiving each logical link control packet data unit, the networkelement is configured to determine whether the radio link control/mediumaccess control protocol layer entity already comprises at least onebuffered logical link control packet data unit.
 42. A network elementaccording to claim 38, wherein the logical link control connectioninformation of the received logical link control packet data unit andthe logical link control connection information of the buffered logicallink control packet data unit are different.
 43. A network elementaccording to claim 38, wherein the logical link control connectioninformation of the received logical link control packet data unit andthe logical link control connection information of the buffered logicallink control packet data unit are similar and the quality of serviceinformation of the received logical link control packet data unit andthe quality of service information of the buffered logical link controlpacket data unit are different.
 44. A network element according to claim38, wherein the network element is further configured, in response tothe logical link control connection information of the received logicallink control packet data unit and the logical link control connectioninformation of the buffered logical link control packet data unit beingsimilar and the quality of service information of the received logicallink control packet data unit and the quality of service information ofthe buffered logical link control packet data unit being quite similar,to change the logical link control connection information of thereceived logical link control packet data unit.
 45. A network elementaccording to claim 38, wherein at the upper protocol layer entity isconfigured to use the logical link control connection information as aninternal logical link control information in. order to handle the,logical link control packet data, unit with appropriate quality ofservice characteristics.
 46. A network element according to claim 38,wherein the received logical link control packet data unit at the radiolink control/medium access control protocol layer entity comprises alogical link control header which indicates at least a service accesspoint indicator at the upper protocol layer entity and the radio linkcontrol/medium access control protocol layer entity is configured toread the service access point indicator.
 47. A network element accordingto claim 46, wherein the logical link control header further indicates awindow number specific for the service access point indicator at theupper protocol layer and the window number is incremented by one whenthe upper protocol layer entity transmits the logical link controlpacket data unit to the radio link control/medium access controlprotocol layer entity.
 48. A network element according to claim 47,wherein the upper protocol layer entity is configure to receive eachlogical link control packet data unit from the radio link control/mediumaccess control layer entity in-sequen6e order according to the windownumber.
 49. A network element according to claim 38, wherein the logicallink control connection information is a service access point indicator.50. A network element according to claim 44, wherein the logical linkcontrol connection information is changed to be an unused service accesspoint indicator.
 51. A network element according to claim 38, whereinthe network element further comprises a buffer configured to buffer thereceived logical link control packet data unit into a packet datatransfer queue for a period of time while a current logical link controlpacket data unit delivery is on-going.
 52. A network element accordingto claim 38, wherein the network element further comprises a timer witha predetermined timeout value configured to begin in response to endingtransmission of a current logical link control packet data unit carryinga higher relative urgency of transmission.
 53. A network elementaccording to claim 38, wherein the radio link control/medium accesscontrol protocol layer entity is configured to interrupt thetransmission of a current logical link control packet data unit carryinga lower relative urgency of transmission in response to receiving a newlogical link control packet data unit carrying a higher relative urgencyof transmission during the transmission of the current logical linkcontrol packet data unit.
 54. A network element according to claim 53,wherein the radio link control/medium access control protocol layerentity is configured to buffer the logical link control packet data unitcarrying the lower relative urgency of transmission by generating alogical link control packet data unit border into a radio link controldata block.
 55. A network element according to claim 38, wherein thewireless packet data network is a general packet radio service network56. A network element according to claim 38, wherein the network elementis one of the following network elements: a serving general packet radiosupport node, a base station controller, mobile switching center and apacket control unit comprising a radio link control/medium accesscontrol unit.
 57. A network element according to claim 38, wherein thequality of service information relates to a logical link control modedefined by the upper protocol entity.
 58. A method comprising: at aradio link control/medium access control protocol layer, receiving atleast one logical link control packet data unit from an upper protocollayer, wherein each logical link control packet data unit belongs to acertain packet data protocol context associated with logical linkcontrol connection information and wherein quality, of service qualityof service information relating to the logical link control connectioninformation is defined for the certain packet data protocol context,reordering each logical link control packet data unit at the radio linkcontrol/medium access control protocol layer according to a relativeurgency of transmission of the logical link control packet data unitwith respect to a buffered logical link control packet data unit basedon at least the logical link control connection information and thequality of service information; and delivering the received logical linkcontrol packet data unit and the buffered logical link control packetdata unit further from the radio link control/medium access controlprotocol layer in reordered order, wherein the method is performed by anetwork element of a wireless packet data network.